Rubber product and method of producing same



Patented Nov. 2, 1943 RUBBER PRODUCT AND METHOD OF PRO- DUCING SAME AlanHenry McIntosh and Harry Edward Pfaff, Hamilton,- Ontario, Canada NoDrawing. Application September 13, 1940,

Serial-No. 356,668 1 4 Claims.

This invention relates to improvements in methods of treating rubberlatex, and has for its primary object the production of novel andimprovedforms ofrubbercompositionarticles. Another object of theinvention is to produce a novel diiiusion of water effect in naturaland/r" modified rubber latex to provide a novelrubber compositionproduct which is stable and of substantially increased bulk and coveringability compared to the rubber content thereof in its previous state.Another object of the invention is to provide a novel rubber compositionproduct a which is capable of improved fabric priming and coatingperformance. Further objects and ad-- vantages of the invention willappear from the specification herein. This application is a continuationin part of our co-pending application of portions of thenatural watercontent fromthe latex through utilization of the tendency of the latextoseparate into component partsduringa so-called creaming"process. Asdistinguished from-the above, 'the present'invention involves no removalofthe originaL-water content from the latex but'does involve the-adding'of additional quantities of water thereinto'in per-- fectly-difiusedform -to produce a novel form of rubber composition which-is ofincreased bulk and stable and not susceptible to coagulation and/orseparation by creaming processes.

In carrying out our invention we first provide a diffusing solution bypreparing an aqueous dispersion of a suitable vegetable gum having thecharacteristics, for the purpose employed, of gum tragacanth. Thediffusing solution is diluted to desired form by addition of Water, andthe filler ingredient, if any is to be used in the composition of theproduct is admixed thereinto. This preparation is then admixed intoeither raw or precured latex, and the composition is ready to be sprayedor brushed or poured or otherwise applied to the surfaces prepared forits reception. If the latex used is of the precured variety; that is,having vulcanizing agents included in its makeup, the composition willset up immediately upon application. However, if the latex used is ofthe raw untreated type a subsequent vulcanizing process will be appliedto the composition to stabilize the rubber content thereof.

The novel rubber composition so produced is substantially stable andwill not coagulate or separate in bulk, and thus remains for longpcriods of time inproper condition for spraying or brushing or othermethods of application. If it is compoundedof the pre-vulcanized type oflatex it will set up immediately upon being so applied at ordinarytemperatures, although under increased temperatures the speed of thesetting will be increased. No pressure is required in this connectionand the resultant product is exceedingly flexible; has comparativelygreat tensile strength; will not check or craze; and will retain thesequalities without deterioration for long periods of time. The Waterdiffusion process of the invention, however, may also be effected inconnection with raw latex prior to the inclusion therein of ingredientsnecessary to subsequently produce vulcanization; and it will beunderstood that in either case the novel diffused latex of the inventionwill be stable and otherwise improved as to form for the purposesintended.

We have found by extensive experiment that the steps in our process mustbe carried out in proper sequence to give the desired results and wewill now describe such process more particularly as well as give typicalformulae.

We first prepare the diffusion agent, as by placing a small quantity ofgum tragacanth in a comparatively larg quantity of distilled water. Wefind that substantially A oz. of gum tragacanth to substantially 2 qts.(4 lbs.) of distilled water is suitable (Formula A).

We then mix /8th of an ounce of Formula A with a further comparativelylarge quantity of distilled Water. Substantially 6 to 8 drops of FormulaA to substantially 1 qt. (2 lbs.) of distilled water is suitable(Formula B).

We then mix 2 lbs. of some suitable filler, such as asbestos flour orthe like, with 2 lbs. of Formula B. If it is desired that the product becolored, suitable color pigments may be added to this mix according tothe color and tint desired (Formula C).

We then pour the product of Formula C into 2 lbs. of pre-cured or vulcanized latex, and mix (Formula D).

Where Formula D is to be applied to fabrics We find it of advantage toemploy a Wetting solution to be applied to such fabrics prior to theapplication of Formula D; or said wetting solution can be included inFormula D for direct application if desired. This wetting solution is initself a high grade Waterproofing and windproofing material where acheaper and lighter rubber covering is desired. Such wetting solution ispreferably brushed into the fabric and may consist of a small quantityof trisodium phosphate or magnesium sulphate dissolved in acomparatively large quantity of distilled water to which a substantiallyequal quantity by weight of pre-cured or vulcanized latex is added andmixed. A wetting solution consisting of from one-half /2) ounce to one(1) ounce of trisodium phosphate (or magnesium sulphate) dissolved infour (4) pounds of distilled water to which is added and mixed four (4)pounds of pre-cured or vulcanized latex is suitable. When our wet- (ormagnesium sulphate) acts as a fibre expanding agent, enabling thecomposition to effectively anchor itself thereto and eflectivelycovitself.

rubber, cork, vermiculite, or the like may be employed. In lieu of thetrisodium phosphate or magnesium sulphate wetting agents, as hereinabovedescribed, any other suitabl form of fibre expanding or wetting agentmay be employed for the purpose explained hereinabove such as borax, forexample, and although the invention has been described herein chiefly byway of example it will be understood that it is not so limited but thatvarious changes may be made ting solution is employed the trisodiumphosphate 4 I therein without departing from the spirit of the.

, invention or the scope of the appended claims.

An important advantage of our compositionis 5 In fact in manyapplications thenecessary equipment can be taken directly onto thejobthus eliminating the need of separate plant and plant equipment. A

Our composition can be employed for manufacturing sheet rubber; therubberi zing of fabrics of all kinds in colors and to other materials inthe form of paint; either byspray gun or brush methods of application.Heavy duty rubberl'of any thickness or desired shape andusinginexpensive fillers such as wood fibres, etc., and applicable tomany uses can be producedby simply mixing the composition cold andtrowelling it into form, then allowing it to set without application ofheat or pressure. Thielatter type of material is particularly adaptableforflexible onepiece molds, as they require no plaster of Paris casesfor support. j I I It will be understood that compositions of theinvention may be compounded of ingredients other than those specificallynamedin the herein'above examples. For instance, in'lieu of gumtragacanth, any other suitable form of vegetable purpose of providingcliffusion of additional Water into the rubber latex ingredient may beemployed. Also, in lieu of the use of asbestos as a' *Weclaim:

1. A rubber composition according to the following formula:

2 lbs. of pre-cured substantially -40 rubber latex; 1 qt. (2 lbs.)distilled water to which has beenpreviously added oz. of a vegetablerubber latex-water difiusing agent composed of a gum solution consistingof 4 oz, gum dissolved in2 qts. (4 lbs.) distilled water; i

2. A rubber composition.a'ccordingpto the-iol-= lowing formula:

2 lbs. of pre-cured latex; 1 qt. (2 lbs.) distilled water to which hasbeen previously added A; oz. of a vegetable rubtragacanth in"2 qts.(4i'lbs.) of'distilled water; adding ,4; oz. of suchflsolution tosubstantially; 1 qt. (2 lbs.) of-distilled'waterto for m,a,.very.

diluted'solution,and adding a quart of thediluted solution tosubstantially 2 lbs. of pre-scured substantially 60-510 rubber latex." tt I J 4; In a process 'for producing a stabilized water diffused rubbercomposition-,thesteps whichflconsist in.-' dissolving substantially A"oz.' of

tragac'anth in 2' qts. (4 lbs.) ;,of*di stilled water, adding AA, oz. ofsuch solution. to substantially 1. qt. (2 lbs.) of distilledgwatertoform's. very diluted solution, adding to this solution 2 'lbsrof fillerand adding the mixture so obtained tosubr stantially .2 lbs. ofpre-cured approximately 60-40 rubberlatex.

. ALAN HENRY MQINTOSH- HARRY EDWARD PFAFF.

substantially 60-40 rubber

